1. Field of the Invention
The invention relates to an improved disk brake having a multiple brake cylinder disposed laterally of the brake disc and movable in a secant direction of the disc.
2. Description of the Prior Art
Conventional disk brakes, in any case those typically used at present, are actuated hydraulically. They have a brake caliper, in which two friction brake linings rest, one on each side of a brake disk disposed between them. A friction brake lining piston that can be actuated hydraulically is received in the brake caliper transversely to the brake disk, and with it a friction brake lining can be pressed against the brake disk. The other friction brake lining can likewise be pressable by a friction brake lining piston against the other side of the brake disk (so-called fixed caliper). It is also known for the brake caliper to be embodied as a so-called floating caliper that is displaceable transversely to the brake disk. Pressing one friction brake lining against one side of the brake disk displaces the brake caliper transversely to the brake disk and presses the other friction brake lining against the other side of the brake disk. As a result of the pressing against the two friction brake linings, the brake disk is braked.
A number of electromechanicaily actuated disk brakes are also known by now, in which a friction brake lining can be pressed against a brake disk by means of an electric motor via a rotation/translation conversion gear. One example of such an electromechanically actuated disk brake is disclosed in International Patent WO 96/03301. The known disk brake has an electric motor, with which, via a spindle drive as the rotation/translation conversion gear, a friction brake lining can be pressed against a brake disk. The electric motor and the spindle drive form an actuating device of the known disk brake and are accommodated in a brake caliper embodied as a floating caliper. The known electromechanically actuated disk brakes have the general disadvantage that in comparison with hydraulically actuated disk brakes that they are large and heavy, because of the electric motor and the rotation/translation conversion gear. Because of their size, the known electromechanically actuated disk brakes are hard to accommodate inside a rim of a vehicle wheel, where disk brakes are usually disposed. The high weight of the electromechanically actuated disk brakes impairs vehicle performance and contact with the road, especially because the disk brake is among what are known as unsprung masses, which for the sake of good vehicle performance and good road contact should be kept low. Another disadvantage of electromechanically actuated disk brakes is high power consumption of their electric motor with an attendant heavy load on an on-board electrical system of a vehicle equipped with the brake.
The known hydraulically and electromechanically actuated disk brakes share the disadvantage that they have no brake force boosting comparable to the brake force boosting of the kind known with the so-called leading-shoe in a drum brake. The leading shoe of a drum brake, on being pressed against the brake drum, is additionally pressed against the brake drum by the rotating brake drum itself, and as a result the braking force is increased.